I will begin this paper by stating in rough outline what I consider
to be the relevance of psychical research to philosophy, and I
shall devote the rest of it to developing this preliminary
statement in detail.

In my opinion psychical research is highly relevant to philosophy
for the following reasons. There are certain limiting principles
which we unhesitatingly take for granted as the framework within
which all our practical activities and our scientific theories are
confined. Some of these seem to be self-evident. Others are so
overwhelmingly supported by all the empirical facts which fall
within the range of ordinary experience and the scientific
elaborations of it (including under this heading orthodox
psychology) that it hardly enters our heads to question them. Let
us call these Basic Limiting Principles. Now psychical research is
concerned with alleged events which seem prima facie to conflict
with one or more of these principles. Let us call any event which
seems prima facie to do this an Ostensibly Paranormal Event.

A psychical researcher has to raise the following questions about
any ostensibly paranormal event which he investigates.

Did it
really happen? Has it been accurately observed and correctly
described?

Supposing that it really did happen and has been
accurately observed and correctly described, does it really
conflict with any of the basic limiting principles? Can it not
fairly be regarded merely as a strange coincidence, not outside the
bounds of probability? Failing that, can it not be explained by
reference to already known agents and laws? Failing that can it not
be explained by postulating agents or laws or both, which have not
hitherto been recognized, but which fall within the framework of
accepted basic limiting principles?

Now it might well have happened that every alleged ostensibly
paranormal event which had been carefully investigated by a
competent psychical researcher was found either not to have
occurred at all, or to have been misdescribed in important
respects, or to be a chance-coincidence not beyond the bounds of
probability, or to be susceptible of an actual or hypothetical
explanation within the 1 framework of the basic limiting
principles. If that had been so, philosophy could afford to ignore
psychical research; for it is no part of its duty to imitate the
White Knight by carrying a mousetrap when it goes out riding, on
the of chance that there might be mice in the saddle. But that is
not how things have in fact turned out. It will be enough at
present to refer to a single instance, viz., Dr. Soal's experiments
on card-guessing with Mr. Shackleton as subject, of which I gave a
full account in Philosophy in 1944. There can be no doubt that the
events described happened and were correctly reported, that the
odds against chance-coincidence piled up to billions to one; and
that the nature of the events, which involved both telepathy and
precognition, conflicts with one or more of the basic limiting
principles.

Granted that psychical research has established the occurrence of
events which conflict with one or more of the basic limiting
principles, one might still ask: How does this concern philosophy?
Well, I think that there are some definitions of 'philosophy',
according to which it would not be concerned with these or any
other newly discovered facts, no matter how startling. Suppose that
philosophy consists in accepting without question, and then
attempting to analyse, the beliefs which are common to contemporary
plain men in Europe and North America, i.e., roughly the beliefs
which such persons acquired uncritically in their nurseries and
have since found no occasion to doubt. Then, perhaps, the only
relevance of psychical research to philosophy would be to show that
philosophy is an even more trivial academic exercise than plain men
had been inclined to suspect. But, if we can judge of what
philosophy is by what great philosophers have done in the past, its
business is by no means confined to accepting without question, and
trying to analyse, the beliefs held in common by contemporary
European and North American plain men. Judged by that criterion,
philosophy involves at least two other closely connected
activities, which I call Synopsis and Synthesis. Synopsis is the
deliberate viewing together of aspects of human experience which,
for one reason or another, are generally kept apart by the plain
man and even by the professional scientist or scholar. The object
of synopsis is to try to find out how these various aspects are
inter-related. Synthesis is the attempt to supply a coherent set of
concepts and principles which shall cover satisfactorily all the
regions of fact which have been viewed synoptically.

Now what I have called the basic limiting principles are plainly of
great philosophical importance in connection with synopsis and
synthesis. These principles do cover very satisfactorily an
enormous range of well-established facts of the most varied kinds.
We are quite naturally inclined to think that they must be all-embracing; we are correspondingly loth to accept any alleged fact
which seems to conflict with them; and, if we are forced to accept
it, we strive desperately to house it within the accepted
framework. But just in proportion to the philosophic importance of
the basic limiting principles is the philosophic importance of any
well-established exception to them. The speculative philosopher who
is honest and competent will want to widen his synopsis so as to
include these facts; and he will want to revise his fundamental
concepts and basic limiting principles in such a way as to include
the old and the new facts in a single coherent system.

The Basic Limiting Principles

I will now state some of the most important of the basic limiting
principles which, apart from the findings of psychical research,
are commonly accepted either as self-evident or as established by
overwhelming and uniformly favourable empirical evidence. These
fall into four main divisions, and in some of the divisions there
are several principles.

(1) General Principles of Causation.

( 1.1) It is self-evidently impossible to have any effects before
it has happened.

(1.2) It is impossible that an event which ends at a certain date
should contribute to cause an event which begins at a later date
unless the period between the two dates is occupied in one or other
of the following ways:

The earlier event initiates a process of change, which continues throughout the period and at the end of it contributes to initiate the later event. Or

the
earlier event initiates some kind of structural modification which
persists throughout the period. This begins to co-operate at the
end of the period with some change which is then taking place, and
together they cause the later event.

(1.3) It is impossible that an event, happening at a certain date
and place, should produce an effect at a remote place unless a
finite period elapses between the two events, and unless that
period is occupied by a causal chain of events occurring
successively at a series of points forming a continuous path
between the two places.

(2) Limitations on the Action of Mind on Matter.

It is impossible
for an event in a person's mind to produce directly any change in
the material world except certain changes in his own brain. It is
true that it seems to him that many of his volitions produce
directly certain movements in his fingers, feet, throat, tongue,
etc. These are what he wills, and he knows nothing about the
changes in his brain. Nevertheless, it is these brain-changes which
are the immediate consequences of his volitions; and the willed
movements of his fingers, etc., follow, if they do so, only as
rather remote causal descendants.

(3) Dependence of Mind on Brain.

A necessary, even if not a
sufficient, immediate condition of any mental event is an event in
the brain of a living body. Each different mental event is
immediately conditioned by a different brain-event. Qualitatively
dissimilar mental events are immediately conditioned by
qualitatively dissimilar brain-events, and qualitatively similar
mental events are immediately conditioned qualitatively similar
brain-events. Mental events which so inter-connected as to be
experiences of the same person are immediately conditioned by
brain-events which happen in the same brain. If two mental events
are experiences of different persons, they are in general
immediately conditioned by brain-events which occur in different
brains. This is not, however, a rule without exceptions. In the
first place, there are occasional but quite common experiences,
occurring in sleep or delirium, whose immediate conditions are
events in a certain brain, but which are so loosely connected with
each other or with the stream of normal waking experiences
conditioned by events in that brain that they scarcely belong to
any recognizable person. Secondly, there are cases of personality,
described and treated by psychiatrists. Here the experiences which
are immediately conditioned by events in a single brain seem to
fall into two or more sets, each of which constitutes the
experiences of a different person. Such different persons are,
however, more closely interconnected in certain ways than two
persons whose respective experiences are immediately conditioned by
events in different brains.

(4) Limitations on Ways of acquiring Knowledge.

(4.1) It is
impossible for a person to perceive a physical event or a material
thing except by means of sensations which that event or thing
produces in his mind. The object perceived is not the immediate
cause of the sensations by which a person perceives it. The
immediate cause of these is always a certain event in the
percipient's brain; and the perceived object is (or is the seat of)
a rather remote causal ancestor of this brain-event. The
intermediate links in the causal chain are, first, a series of
events in the space between the perceived object and the
percipient's body; then an event in a receptor organ, such as his
eye or ear; and then a series of events in the nerve connecting
this receptor organ to his brain. When this causal chain is
completed, and a sensory experience arises in the percipient's
mind, that experience is not a state of acquaintance with the
perceived external object, either as it was at the moment when it
initiated this sequence of events or as it now is. The qualitative
and relational character of the sensation is wholly determined by
the event in the brain which is its immediate condition; and the
character of the latter is in part dependent on the nature and
state of the afferent nerve, of the receptor organ, and of the
medium between the receptor and the perceived object.

(4.2) It is impossible for A to know what experiences B is having
or has had except in one or other of the following ways.

By
hearing and understanding sentences, descriptive of that
experience, uttered by B, or by reading and understanding such
sentences, written by B, or reproductions or translations of them.
(I include under these headings messages in Morse or any other
artificial language which is understood by A.)

By hearing and
interpreting cries which B makes, or seeing and interpreting his
gestures, facial expressions, etc.

By seeing, and making
conscious or unconscious inferences from, persistent material
records, such as tools, pottery, pictures, etc., which B has made
or used in the past. (I include under this head seeing copies or
transcriptions, etc., of such objects.)

Similar remarks apply, mutatis mutandis, to the conditions under
which A can acquire from B knowledge of facts which B knows or
acquaintance with propositions which B contemplates. Suppose that
B knows a certain fact or is contemplating a certain proposition.
Then the only way in which A can acquire from B knowledge of that
fact or acquaintance with that proposition is by B stating it in
sentences or other symbolic expressions which A can understand, and
by A perceiving those expressions themselves, or reproductions or
translations of them, and interpreting them.

(4.3) It is impossible for a person to forecast, except by chance,
that an event of such and such a kind will happen at such and such
a place and time except under one or other of the following
conditions.

By making an inference from data supplied to him by
his present sensations, introspections, or memories, together with
his knowledge of certain rules of sequence which have hitherto
prevailed in nature.

By accepting from others, whom he trusts,
either such data or such rules or both, and then making his own
inferences; or by accepting from others the inferences which they
have made from data which they claim to have had and regularities
which they claim to have verified.

By non-inferential
expectations, based on associations which have been formed by
certain repeated sequences in his past experience and which are now
stimulated by some present experience.

It should be noted here that, when the event to be forecast by a
person is a future experience or action of himself or of another
person, we have a rather special case, which is worth particular
mention, although it falls under one or other of the above head
ings. A may be able to forecast that he himself will have a certain
experience or do a certain action, because he knows
introspectively that he has formed a certain intention. He may be
able to forecast that B will have a certain experience or do a
certain action, because he has reason to believe, either from B's
explicit statements or from other signs, that B has formed a
certain intention.

(4.4) It is impossible for a person to know or have reason to
believe that an event of such and such a kind happened at such and
such a place and time in the past except under one or another of
the following conditions.

That the event was an
experience which he himself had during the lifetime of his present
body; that this left a trace in him which has lasted until now; and
that this trace can be stimulated so as to give rise in him to a
memory of that past experience.

That the event was one which
he witnessed during the lifetime of his present body; that the
experience of witnessing it left a trace in him which has lasted
till now; and that he now remembers the event witnessed, even
though he may not be able to remember the experience of witnessing
it.

That the event was experienced or witnessed by someone
else, who now remembers it and tells this person about it.

That the event was experienced or witnessed by someone (whether
this person him self or another), who made a record of it either at
the time or after wards from memory; that this record or copies or
translations of it have survived; and that it is now perceptible by
and intelligible to this person.
(These four methods may be
summarized under the heads of present memory, or testimony based on
present memory or on records of past perceptions or memories.)

Explicit or implicit inference, either made by the person himself
or made by others and accepted by him on their authority, from data
supplied by present sense-perception, introspection, or memory,
together with knowledge of certain laws of nature.

I do not assert that these nine instances of basic limiting principle are exhaustive, or that they are all logically independent of
each other. But I think that they will suffice as examples of
important restrictive principles of very wide range, which are
commonly accepted to-day by educated plain men and by scientists in
Europe and America.

General Remarks on Psychical
Research

I turn now to psychical research. Before going into detail I will
make some general remarks about its data, methods and affiliations.

(1) The subject may be, and has been, pursued in two ways.

As a critical investigation of accounts of events
which, if they happened at all, did so spontaneously under
conditions which had not been deliberately pre-arranged and cannot
be repeated at will.

As an experimental study, in which the
investigator raises a definite question and pre-arranges the
conditions so that the question will be answered in this, that, or
the other way according as this, that, or the other observable
event happens under the conditions.

An extreme instance of
the former is provided by the investigation of stories of the
following kind. A asserts that he has had an hallucinatory waking
experience of a very specific and uncommon kind, and that this
experience either imitated in detail or unmistakably symbolized a
certain crisis in the life of a certain other person B, e.g. death
or a serious accident or sudden illness, which happened at roughly
the same time. A claims that B was many miles away at the time,
that he had no normal reason to expect that such an event would
happen to B, and that he received no information of the event by
normal means until afterwards. An extreme instance of the latter is
provided by the card-guessing experiments of Dr. Soal in England or
of Professor Rhine and his colleagues in U.S.A.

Intermediate between these two extremes would be any carefully
planned and executed set of sittings with a trance-medium, such as
the late Mr. Saltmarsh held with Mrs. Warren Elliott and described
in Vol. XXXIX of the S.P.R. Proceedings. In such cases the
procedure is experimental at least in the following respects. A
note-taker takes down everything that is said by sitter or medium,
so that there is a permanent record from which an independent judge
can estimate to a considerable extent whether the medium was
'fishing' and whether the sitter was inadvertently giving hints.
Various techniques are used in order to try to estimate objectively
whether the statements of the medium which are alleged to concern
a certain dead person do in fact fit the peculiarities of that
person and the circumstances of his life to a significantly closer
degree than might be expected from mere chance coincidence. On the
other hand, the procedure is non-experimental in so far as the
sitter cannot ensure that the utterances of the entranced medium
shall refer to pre-arranged topics or answer pre-arranged
questions. He must be prepared to hear and to have recorded an
immense amount of apparently irrelevant twaddle, in the hope that
something importantly relevant to his investigation may be embedded in it.

(2) It seems to me that both methods are important, and that they
stand in the following relations to each other. The sporadic cases,
if genuine and really paranormal, are much richer in content and
more interesting psychologically than the results of experiment
with cards or drawings. In comparison with the latter they are as
thunderstorms to the mild electrical effects of rubbing a bit of
sealing-wax with a silk handkerchief. But, taken in isolation from
the experimentally established results, they suffer from the
following defect. Any one of them separately might perhaps be
regarded as an extraordinary chance coincidence; though I do not
myself think that this would be a reasonable view to take of them
collectively, even if they were not supported by experimental
evidence, when one considers the number and variety of such cases
which have stood up to critical investigation. But, however that
may be, there is no means of estimating just how unlikely it is
that any one such case, or the whole collection of them, should be
mere chance coincidence.

Now, if there were no independent experimental evidence for
telepathy, clairvoyance, precognition, etc., it would always be
possible to take the following attitude towards the sporadic cases.
'Certainly,' it might be said, 'the evidence seems water-tight, and
the unlikelihood of mere chance coincidence seems enormous, even
though one cannot assign a numerical measure to it. But, if the
reported events were genuine, they would involve telepathy or
clairvoyance or precognition. The antecedent improbability of these
is practically infinite, whilst there is always a possibility of
mistake or fraud even in the best attested and most carefully
checked reports of any complex incident which cannot be repeated at
will. And there is no coincidence so detailed and improbable that
it may not happen occasionally in the course of history. Therefore, it is more reasonable to hold that even the best attested
sporadic cases were either misreported or were extraordinary
coincidences than to suppose that they happened as reported and
that there was a causal connection between A's experience and
the nearly contemporary event in B's life to which it seemed to
correspond.'

Now, whether this attitude would or would not be reasonable in the
absence of experimental cases, it is not reasonable when the latter
are taken into account and the sporadic cases are considered in
relation to them. In card-guessing experiments, e.g. we can assign
a numerical value to the most probable number of correct guesses in
a given number of trials on the supposition that chance coincidence
is the only factor involved. We can also assign a numerical value
to the probability that, if chance coincidence only were involved,
the actual number of correct guesses would exceed the most probable
number by more than a given amount. We can then go on repeating the
experiments, under precisely similar conditions, hundreds or
thousands of times, with independent witnesses, elaborate checks on
the records, and so on.

Now Dr. Soal, Professor Rhine and his colleagues, and Mr. Tyrrell,
working quite independently of each other, have found that certain
subjects can cognize correctly, with a frequency so greatly above
chance-expectation that the odds against such an excess being
fortuitous are billions to one, what another person has been and is
no longer perceiving, what he is contemporaneously perceiving, and
what he will not begin to perceive until a few seconds later. This
happens under conditions where there is no possibility of relevant
information being conveyed to the subject by normal sensory means,
and where there is no possibility of his consciously or unconsciously inferring the future event from any data available to
him at the time. It follows that the antecedent improbability of
paranormal cognition, whether post-cognitive, simultaneous, or pre-cognitive, cannot reasonably be treated as practically infinite in
the sporadic cases. These paranormal kinds of cognition must be
reckoned with as experimentally verified possibilities, and, in
view of this, it seems reasonable to accept and to build upon the
best attested sporadic cases.

(3) The findings of psychical research should not be taken in
complete isolation. It is useful to consider many of them in
connexion with certain admitted facts which fall within the range
of orthodox abnormal psychology and psychiatry. The latter facts
form the best bridge between ordinary common sense and natural
science (including normal psychology), on the one hand, and
psychical research, on the other. As I have already mentioned in
connexion with Principle 3, the occurrence of dreams and delirium
and the cases of multiple personality would suffice, even in the
absence of all paranormal phenomena, to qualify the dogma that, if
two mental events are experiences of different persons, they are
always immediately conditioned by events in different brains. We
can now go further than this. There are obvious and important
analogies between the phenomena of trance-mediumship and those of
alternating personality unaccompanied by alleged paranormal
phenomena. Again, the fact of dreaming, and the still more startling facts of experimentally induced hypnotic hallucinations, show
that each of us has within himself the power to produce, in
response to suggestions from within or without, a more or less
coherent quasi-sensory presentation of ostensible things and
persons, which may easily be taken for a scene from the ordinary
world of normal waking life. Cases of veridical hallucination
corresponding to remote contemporary events, instances of haunted
rooms, and so on, are slightly less incredible when regarded as due
to this normal power, abnormally stimulated on rare occasions by a
kind of hypnotic suggestion acting telepathically. It is certainly
wise to press this kind of explanation as far as it will go, though
one must be prepared for the possibility that it will not cover all
the cases which we have to accept as genuine.

(4) If paranormal cognition and paranormal causation are facts,
then it is quite likely that they are not confined to those very
rare occasions on which they either manifest themselves sporadically in a spectacular way or to those very special conditions in
which their presence can be experimentally established. They may
well be continually operating in the background of our normal
lives. Our understanding of, and our misunderstandings with, our
fellow-men; our general emotional mood on certain occasions; the
ideas which suddenly arise in our minds without any obvious
introspectable cause; our unaccountable immediate emotional
reactions towards certain persons; our sudden decisions where the
introspectable motives seem equally balanced; and so on; all these
may be in part determined by paranormal cognition and paranormal
causal influences.

In this connexion it seems to me that the following physical
analogy is illuminating. Human beings have no special sensations in
presence of magnetic fields. Had it not been for the two very
contingent facts that there are loadstones, and that the one
element (iron) which is strongly susceptible to magnetic influence
is fairly common on earth, the existence of magnetism might have
remained unsuspected to this day. Even so, it was regarded as a
kind of mysterious anomaly until its connexion with electricity was
discovered and we gained the power to produce strong magnetic
fields at will. Yet, all this while, magnetic fields had existed,
and had been producing effects, whenever and wherever electric
currents were passing. Is it not possible that natural mediums
might be comparable to loadstones; that paranormal influences are
as pervasive as magnetism; and that we fail to recognize this only
because our knowledge and control of them are at about the same
level as were men's knowledge and control of magnetism when Gilbert
wrote his treatise on the magnet?

Established
Results of Psychical Research

We can now consider in detail some well-established results of
psychical research, which seem prima facie to conflict with one or
more of our basic limiting principles.

I will begin with paranormal cognition. As I have said, the
existence of this has been abundantly verified experimentally, and
this fact makes it reasonable to accept the best attested and most
carefully investigated of the sporadic cases as genuine instances
of it. The following general remarks seem to be worth making about
it.

(1) In much of the experimental work the word 'cognition' must be
interpreted behaviouristically, at least as regards the subject's
introspectable mental processes. In Dr. Soal's experiments, e.g.
the agent acts as if he often knows what card has been, or is now
being, or very soon will be, looked at by the agent in an adjoining
room. He does so in the following sense. He already knows that each
of the cards bears a picture of one or other of a certain set of
five animals. Whenever he receives a signal to inform him that the
agent has just turned up a card he immediately writes down the
initial letter of the name of one of these five animals. It is
found that the letter thus written agrees with the name of the
animal on the card which will next be turned up by the agent so
often that the odds against such an excess of hits being a mere
matter of chance are about 1035 to 1. Now the subject
says that he writes down the initial letter 'almost automatically'
and that he seldom gets a mental image of the animal depicted.
Again, he is not consciously aiming at guessing the nature of the
card which will next be turned up. In the earlier experiments at
least he was aiming at the card which he knew that the agent was
then looking at. Lastly, a whole series of 25 cards are turned up
in fairly rapid succession, the average interval being about 2.5
seconds. The behaviouristic character of the whole process is even
more marked in Mr. Tyrrell's experiments. If there is genuine
cognition, it takes place at some level which is not introspectable
by the subject.

(2) A most interesting fact, which has been noted by several
experimenters, is the occurrence of significantly negative results,
i.e. scores which are so much below chance-expectation that the
odds against getting such poor results merely by chance are
enormous. In order consistently to score below chance-expectation
the subject must presumably know at some level of his consciousness
what the target card is, and must for some reason be impelled to
write down some other alternative.

(3) It has been common for writers and experimenters in psychical
research to subdivide paranormal cognition into telepathy,
clairvoyance, precognition, etc. It should be noted, however, that
the establishment of the occurrence of precognition makes it
difficult in the case of many successful experiments to classify
the results with confidence under any one of these heads. They are
evidence for paranormal cognition of some kind, but it is uncertain
of which kind.

I will now go a little further into this matter. We must allow for
the following alternatives, which do not necessarily exclude each
other. A causal condition of A's present paranormal cognition of x
might be of any of the following kinds.

His own
future normal cognition of x. This may be called a precognitive
autoscopic condition.

Another person's past, contemporary, or
future normal cognition of x. This may be called a telepathic
condition, and, according to the temporal circumstances, it will be
called post-cognitive, simultaneous, or precognitive.

Now in any actual case of paranormal cognition we can raise the
question, with regard to each of these conditions or any
combination of then, whether it was necessary and whether it was
sufficient. It cannot have been necessary if the instance occurred
in its absence. It cannot be known to have been sufficient, though
it may in fact have been so, if others of these conditions were
fulfilled in addition to it. If we could verify the occurrence of
a paranormal cognition in a case where all these conditions were
known to be absent, we might describe it as an instance of pure
clairvoyance, which might be either post-cognitive, simultaneous,
or precognitive. It should be noted that the word 'clairvoyance',
as I have just defined it, is a negative term. It denotes merely
the occurrence of paranormal cognition in the absence of the
autoscopic and the telepathic conditions. It is plainly difficult
to imagine a case, in regard to which one could feel sure that it
was purely clairvoyant. In order to be sure that A's ostensible
cognition of x was not conditioned either autoscopically or
telepathically we should have to know that neither A himself nor
anyone else would ever come to cognize x normally and that no one
else either had cognized or was cognizing x normally at the time
when A's experience occurred. It is plain that all these negative
conditions are seldom fulfilled. And, if they were, it is hard to
see how A himself or anyone else could ascertain whether A's
ostensible cognition of x was veridical or delusive.

It does not follow that there are no cases of clairvoyance. For one
or other of the autoscopic or telepathic conditions might be
present in a particular case of paranormal cognition, but might
either be not operating at all or be merely supplementing
clairvoyance. Nor does it follow that there might not be cases in
which an explanation in terms of autoscopy or telepathy, though
possible, would be so far-fetched that it might be more plausible
to describe them as instances of clairvoyance.

In Soal's experiments the autoscopic condition was absent; for the
subject was not afterwards informed of the actual cards which had
been turned up, and so could not have been autoscopically
precognizing his own future state of normal information. Again,
Soal interspersed among the normal runs of guesses, in which the
agent took up the card and looked at it, other runs in which the
agent merely touched the back of the card without looking at it.
These variations were introduced sometimes with and sometimes
without telling the subject. Now, in the interspersed runs the
number of successful guesses sank to the level of chance-expectation, whilst in the normal runs, among which they were
interspersed, it was very significantly above chance-expectation.
So it would seem that, with this subject and these agents at any
rate, the telepathic condition (in the precognitive form) is
necessary to success.

In Mr. Tyrrell's experiments, however (S.P.R. Proceedings, Vol.
XLIV), the subject scored very significantly above chance-expectation under conditions where precognitive autoscopy and every
kind of telepathy seem to be excluded. These experiments were of a
very different nature and with a different subject. Here the agent
would press one or other of five keys connected with small lamps in
five light-tight boxes. The subject had to open the lid of the box
in which she believed that the lamp had been lighted. Successes and
failures were scored mechanically on a moving band of paper.
Tyrrell introduced a commutator between the keys and the lamps. The
effect of this was that the same key would light different lamps on
different occasions, and that the agent would never know which lamp
he was lighting when he pressed any particular key. Moreover, the
automatic recorder merely marked success or failure; it did not
show which box was responsible for any particular success. So it
would not help the subject if she were precognitively aware either
of her own or of the experimenter's subsequent normal perception of
the record. It could seem, therefore, that there is good evidence
for paranormal cognition under purely clairvoyant conditions. Good
evidence under these conditions is also claimed by Professor Rhine
and his colleagues.

The Established Results and the
Basic Limiting Principles

We are now in a position to confront our nine basic limiting
principles with the results definitely established by experimental
psychical research.

(1) Any paranormal cognition obtained under precognitive
conditions, whether autoscopic or telepathic, seems prima facie to
conflict with Principle 1.1. For the occurrence of the cognition
seems to be in part determined by an event which will not happen
until after it has occurred: e.g. in Soal's experiments the
subject's act of writing down the initial letter of the name of a
certain animal seems in many cases to be in part determined by the
fact that the agent will a few seconds later be looking at a card
on which that animal is depicted.

It also conflicts with Principle 4.3. For we should not count the
forecasting of an event as an instance of paranormal cognition,
unless we had convinced ourselves that the subject's success could
not be accounted for either by his own inferences, or by his
knowledge of inferences made by others, or by non-inferential
expectations based on associations formed in his mind by repeated
experiences of sequence in the past. Now in the case of such
experiments as Dr. Soal's and Professor Rhine's all these kinds of
explanation are ruled out by the design of the experiment. And in
some of the best cases of sporadic precognition it seems
practically certain that no such explanation can be given.

It seems to me fairly plain that the establishment of paranormal
precognition requires a radical change in our conception of time,
and probably a correlated change in our conception of causation. I
do not believe that the modifications introduced into the notion of physical time and space by the Theory of Relativity are here relevant, except in the very general sense that they help to free our minds from inherited prejudices and to make us more ready to
contemplate startling possibilities in this department. Suppose,
e.g. that a person has an autoscopic paranormal precognition of
some experience which he will have some time later. I do not see
that anything that the Theory of Relativity tells us about the
placing and dating of physical events by means of measuring-rods
and clocks regulated by light-signals can serve directly to make
such a fact intelligible.

(2) Paranormal cognition which takes place under conditions which
are telepathic but not precognitive does not conflict with
Principles 1.1 and 4.3. But it does seem prima facie to conflict
Principle 4.2, and also with Principles 2, 1.3 and 3.

As regards Principle 4.2, we should not count A's knowledge of a
contemporary or past experience of B's as paranormal, unless we had
convinced ourselves that A had not acquired it by any of the normal
means enumerated in that Principle. The same remarks apply mutatis
mutandis to A's acquiring from B knowledge of a fact known to the
latter, or to A's becoming aware of a proposition which B is
contemplating. Now, in the experimental cases of simultaneous or
post-cognitive telepathy all possibilities of normal communication
are carefully excluded by the nature of the experimental
arrangements. And in the best of the sporadic cases there seems
to be no reasonable doubt that they were in fact excluded. In many
well attested and carefully investigated cases the two persons
concerned were hundreds of miles apart, and out of reach of
telephones and similar means of long-distance communication, at
the time when the one had an experience which corresponded to an
outstanding and roughly contemporary experience in the other.

If non-precognitive telepathy is to be consistent with Principle 3,
we must suppose that an immediate necessary condition of A's
telepathic cognition of B's experience is a certain event in A's
brain. If it is to be consistent with Principle 2, we cannot
suppose that this event in A's brain is produced directly by the
experience of which A telepathically cognizes. For Principle 2
asserts that the only change in the material world which an event
in a person's mind can directly produce is a change in that
person's own brain. If, further, it is to be consistent with
Principle 1.3, the event in B's brain, which is the immediate
consequence in the material world of his experience, cannot
directly cause the event in A's brain which is the immediate
necessary condition of A's telepathic cognition of B's experience.
For there is a spatial gap between these two brain events; and
Principle 1.3 asserts that a finite period must elapse and that this
must be occupied by a causal chain of events occur ring
successively at a series of points forming a continuous path
between the two events.

So, if non-precognitive telepathy is to be reconciled with
Principles 3, 2 and 1.3 taken together, it must be thought of as
taking place in the following way. B's experience has as its
immediate concomitant or consequence a certain event in B's brain.
This initiates some kind of transmissive process which, after an
interval of time, crosses the gap between B's body and A's body.
There it gives rise to a certain change in A's brain, and this is
an immediate necessary condition of A's telepathic cognition of B's
experience. I suspect that many people think vaguely of non-precognitive telepathy as a process somewhat analogous to the
broadcasting of sounds or pictures. And I suspect that familiarity
with the existence of wireless broadcasting, together with
ignorance of the nature of the processes involved in it, has led
many of our contemporaries, for completely irrelevant and invalid
reasons, to accept the possibility of telepathy far more readily
than their grandparents would have done, and to ignore the
revolutionary consequences of the admission.

There is nothing in the known facts to lend any colour to this
picture of the process underlying them. There is nothing to suggest
that there is always an interval between the occurrence of an
outstanding experience in B and the occurrence of a paranormal
cognition of it in A, even when B's and A's bodies are very widely
separated. When there is an interval there is nothing to suggest
that it is correlated in any regular way with the distance between
the two person's bodies at the time. This in itself would cast
doubt on the hypothesis that, in all such cases, the interval is
occupied by a causal chain of events occurring successively at a
series of points forming a continuous path between the two places.
Moreover, the frequent conjunction in experimental work of
precognitive with non-precognitive telepathy under very similar
conditions, makes it hard to believe that the processes involved in
the two are fundamentally different. But it is plain that the
picture of a causal chain of successive events from an event in B's
brain through the intervening space to an event in A's brain
cannot represent what happens in precognitive telepathy. Then,
again, there is no independent evidence for such an intermediating
causal chain of events. Lastly, there is no evidence for holding
that an experience of B's is more likely to be cognized
telepathetically by A if he is in B's neighbourhood at the time
than if he is far away; or that the telepathic cognition, if it
happens, is generally more vivid or detailed or correct in the
former case than in the latter.

I do not consider that any of these objections singly, or all of
them together, would conclusively disprove the suggestion that non-precognitive telepathy is compatible with Principles 3, 2 and 1.3. The suggested account of the process is least unplausible when
B's original experience takes the form of a visual or auditory
perception or image, and A's corresponding experience takes the
form of a visual or auditory image or hallucinatory quasi-perception resembling B's in considerable detail. But by no means
all cases of non-precognitive telepathy take this simple form.

I can imagine cases, though I do not know whether there are any
well-established instances of them, which would be almost
impossible to reconcile with the three Principles in question. Suppose, e.g. that B, who understands Sanskrit, reads attentively a
passage in that tongue enunciating some abstract and characteristic
metaphysical proposition. Suppose that at about the same time his
friend A, in a distant place, not knowing a word of Sanskrit, is
moved to write down in English a passage which plainly corresponds
in meaning. Then I do not see how the physical transmission theory
could be stretched to cover the case.

(3) If there be paranormal cognition under purely clairvoyant
conditions, it would seem to constitute an exception to Principle
4.1. For it would seem to be analogous to normal perception of a
physical thing or event, in so far as it is not conditioned by the
subject's own future normal knowledge of that object, or by any
other person's normal knowledge of it, whether past, contemporary,
or future. And yet, so far as one can see, it is quite unlike
ordinary sense-perception. For it does not take place by means of
a sensation, due to the stimulation of a receptor organ by a
physical process emanating from the perceived object and the
subsequent transmission of a nervous impulse from the stimulated
receptor to the brain.

To sum up about the implications of the various kinds of paranormal cognition. It seems plain that they call for very radical
changes in a number of our basic limiting principles. I have the
impression that we should do well to consider much more seriously
than we have hitherto been inclined to do the type of theory which
Bergson put forward in connexion with normal memory and sense
perception. The suggestion is that the function of the brain and
nervous system and sense-organs is in the main eliminative and not
productive. Each person is at each moment potentially capable of
remembering all that has ever happened to him and of perceiving
everything that is happening anywhere in the universe. The function
of the brain and nervous system is to protect us from being
overwhelmed and confused by this mass of largely useless and
irrelevant knowledge, by shutting out most of what we should
otherwise perceive or remember at any moment, and leaving only that
very small and special selection which is likely to be practically
useful. An extension or modification of this type of theory seems
to offer better hopes of a coherent synthesis of normal and
paranormal cognition than is offered by attempts to tinker with the
orthodox notion of events in the brain and nervous system
generating sense-data.

Another remark which seems relevant here is the following. Many
contemporary philosophers are sympathetic to some form of the so-called 'verification principle', i.e. roughly that a synthetic
proposition is significant if and only if we can indicate what kind
of experiences in assignable circumstances would tend to support or
to weaken it. But this is generally combined with the tacit
assumption that the only kinds of experience which could tend to
support or to weaken such a proposition are sense-perceptions,
introspections, and memories. If we have to accept the occurrence
of various kinds of paranormal cognition, we ought to extend the
verification principle to cover the possibility of propositions
which are validated or invalidated by other kinds of cognitive
experience beside those which have hitherto been generally
admitted.

The Less Firmly Established Results and
the Basic Principles

So far I have dealt with paranormal facts which have been
established to the satisfaction of everyone who is familiar with
the evidence and is not the victim of invincible prejudice. I shall
end my paper by referring to some alleged paranormal phenomena
which are not in this overwhelmingly strong position, but which
cannot safely be ignored by philosophers.

(1) Professor Rhine and his colleagues have produced what seems to
be strong evidence for what they call psycho-kinesis under
experimental conditions. The experiments take the general form of
casting dice and trying to influence by volition the result of the
throw. Some of these experiments are open to one or another of
various kinds of criticism: and, so far as I am aware, all attempts
made in England to reproduce the alleged psycho-kinetic effect
under satisfactory conditions have failed to produce a sufficient
divergence from chance-expectation to warrant a confident belief
that any paranormal influence is acting on the dice. But the fact
remains that a considerable number of the American experiments seem
to be immune to these criticisms, and that the degree of divergence
from chance-expectation in these is great enough to be highly
significant.

Along with these experimental results should be taken much more
spectacular ostensibly telekinetic phenomena which are alleged to
have been observed and photographed, under what seem to be
satisfactory conditions, in presence of certain mediums. Perhaps
the best attested case is that of the Austrian-medium Rudi
Schneider, investigated by several competent psychical researchers
in England and in France between the first and the second world
wars.

We ought, therefore, to keep something more than an open mind
towards the possibility that psycho-kinesis is a genuine fact. If
it is so, we seem prima facie to have an exception to Principle 2.
a For, if psycho-kinesis really takes place in Rhine's experiments,
an event in the subject's mind, viz. a volition that the dice shall
fall in a certain way, seems to produce directly a change in a part
of the material world outside his body, viz. in the dice. An
alternative possibility would be that each of us had a kind of
invisible and intangible but extended and dynamical 'body',
beside his ordinary visible and tangible body; and that it puts
forth 'pseudopods' which touch and affect external objects. (The
results of Osty's experiments with Rudi Schneider provide fairly
strong physical evidence for some such theory as this, however
fantastic it may seem.)

(2) Lastly, there is the whole enormous and very complex and
puzzling domain of trance mediumship and ostensible communications
from the surviving spirits of specified persons who have died. To
treat this adequately a whole series of papers would be needed.
Here I must content myself with the following brief remarks.

There is no doubt that, amongst that flood of dreary irrelevance
and high-falutin twaddle which is poured out by trance-mediums,
there is a residuum of genuinely paranormal material of the
following kind. A good medium with a good sitter will from time to
time give information about events in the past life of a dead person who claims to be communicating at the time. The medium may
have had no chance whatever to gain this information normally, and
the facts asserted may at the time be unknown to the sitter or to
anyone else who has sat with the medium. They may afterwards be
verified and found to be highly characteristic of the ostensible
communicator. Moreover, the style of the communication, and the
mannerisms and even the voice of the medium while speaking, may
seem to the sitter to be strongly reminiscent of the ostensible
communicator. Lastly, there are a few cases in which the statements
made and the directions given to the sitter seem to indicate the
persistence of an intention formed by the dead man during his
lifetime but not carried out. There are other cases in which the
ostensible communicator asserts, and the nature of the
communications seems to confirm, that action is being taken by him
and others at and between the sittings in order to provide evidence
of survival and identity.

Some of the best cases, if taken by themselves, do strongly suggest
that the stream of interconnected events which constituted the
mental history of a certain person is continued after the death of
his body, i.e. that there are post-mortem experiences which are
related to each other and to the ante-mortem experiences of this
person in the same characteristic way in which his ante-mortem
experiences were related to each other. In most of these cases the
surviving person seems to be communicating only indirectly through
the medium. The usual dramatic form of the sitting is that the
medium's habitual trance-personality, speaking with the medium's
vocal organs, makes statements which claim to be reports of what
the surviving person is at the time directly communicating to it.
But in some of the most striking cases the surviving person seems
to take control of the medium's body, to oust both her normal
personality and her habitual trance-personality, and to speak in
its own characteristic voice and manner through the medium's lips.

If we take these cases at their face value) they seem flatly to
contradict Principle 3. For this asserts that every different
mental event is immediately conditioned by a different brain-event,
and that mental events which are so interconnected as to be
experiences of the same person are immediately conditioned by
brain-events which occur in the same brain.

But I do not think that we ought to take the best cases in
isolation from the mass of mediumistic material of a weaker kind.
And we certainly ought not to take them in isolation from what
psychiatrists and students of abnormal psychology tell us about
alternations of personality in the absence of paranormal
complications. Lastly, we ought certainly to view them against the
background of established facts about the precognitive, telepathic
and clairvoyant powers of ordinary embodied human beings. There is
no doubt at all that the best phenomena of trance-mediumship
involve paranormal cognition of a high order. The only question is
whether this, combined with alternations of personality and
extraordinary but not paranormal powers of dramatization, will not
to account for the phenomena which prima facie suggest so strongly
that some persons survive the death of their bodies and communicate
through mediums. This I regard as at present an open question.

In conclusion I would make the following remark. The establishment
of the existence of various forms of paranormal cognition has in
one way helped and in another way hindered the efforts of those who
seek to furnish empirical proof of human survival. It has helped,
in so far as it has undermined that epiphenomenalist view of the
human mind and all its activities, which all other known facts seem
so strongly to support, and in view of which the hypothesis of
human survival is antecedently so improbable as not to be worth
serious consideration. It has hindered, in so far as it provides
the basis for a more or less plausible explanation, in terms of
established facts about the cognitive powers of embodied human
minds, of phenomena which might otherwise seem to require the
hypothesis of survival.